StringIndexOutOfBoundsException- Crossword Solver App.

[numbskull20]

I'm working on a crossword solver that takes user input e.g. h**s*. A text file (dictionary.txt) which contains a list of about 250,000 words is read and matching words are returned i.e. horse, house, etc.

The program kind of works sometimes but mostly i keep getting a StringIndexOutOfBoundsException. I need help. Here is the code so far:

import java.util.ArrayList;
import java.util.Collection;

public class MatchingWithWildcards {

	public static Collection<String> getMatches(String t, String p) {
		Collection<String> result = new ArrayList<String>();
		for (int i = 0; i < t.length(); i++) {
			int j = 0;
			int h = i;
			int n = p.length();
			
			while(true){
				int L = SimpleLongestCommonExtension.longestCommonExtension(p, j, t, h);
				
				if (j + 1 + L == n + 1) {
				    result.add(t.substring(i, i + n));
				    break;
				}
				
				if (((j + L) < p.length() && p.charAt(j + L) == '*')
				        || ((h + L) < t.length() && t.charAt(h + L) == '*')) {
				    j = j + L + 1;
				    h = h + L + 1;
				} else
				    break;
			}
			
		}
		return result;
	}
}

public class SimpleLongestCommonExtension {

	public static int longestCommonExtension(String t1, int i1, String t2, int i2) {
	    int res = 0;
	    for (int i = i1; i < t1.length() && i2 < t2.length(); i++, i2++) {
	        if (t1.charAt(i) == t2.charAt(i2))
	            res++;
	        else
	            return res;
	    }
	    return res;
	}
}

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;
import java.util.Collection;

public class Test {
	
	public static void main(String[] args) {
		
		try {
		    BufferedReader in = new BufferedReader(new FileReader("dictionary.txt"));
		    String str;
		    String input = "aa******";
		    
		    while ((str = in.readLine()) != null) {
		    	
		    	if(str.length() == input.length()){
		    		MatchingWithWildcards wild = new MatchingWithWildcards();
				    
				    Collection<String> results = wild.getMatches(str, input);
			    	if(!results.isEmpty()){
			    		System.out.println(results);
			    	}
		    	}
		    }
		    in.close();
		} 
		catch (IOException e) {
			System.out.println(e.toString());
		}
	}
}

OUTPUT:

[aardvark]
[aardwolf]
Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 9
at java.lang.String.substring(String.java:1934)
at gmit.MatchingWithWildcards.getMatches(MatchingWith Wildcards.java:20)
at gmit.Test.main(Test.java:23)

[Tolls]

t.substring(i, i + n)

What happens when i = t.length() - 1 (which is allowed by your loop criteria)?

ETA: Actually it's should be what happens when i = t.length() - p.length()?

[numbskull20]

So, how do I fix it? I'm not very good with loops to be honest

[numbskull20]

It's fixed. I changed the line

for (int i = 0; i <= t.length(); i++)

to

for (int i = 0; i <= t.length() - p.length(); i++)